This invention relates to containers, and more particularly to large containers fashioned of corrugated paperboard or other similar resilient, stiff and foldable sheet stock. Very large containers fashioned of corrugated paperboard are often termed bulk boxes because of their size. Bulk boxes are well known in the packaging art and some exhibit the property of being collapsed prior to being filled, and also of being collapsed subsequent to emptying, for reshipment and reuse.
Those bulk boxes to which this invention relates are employed with slip sheets. As used in this art, a slip sheet is often a separate sheet of corrugated paperboard, or a sheet of fiber board, or any other unitary sheet which is placed beneath a bulk box, with a portion of the slip sheet, at least along one edge of the box, extending beyond a respective sidewall of the box so as to thereby define a clamping edge portion. A slip sheet lift truck, similar to a forklift truck, is provided with a clamp which engages the clamping edge portion of the slip sheet and pulls the slip sheet, together with the loaded bulk box thereon, onto the platform of the slip sheet lift truck. The bulk box may now be transported to another location, as for example, to a stacking location.
Slip sheets may also be used with conventional forklift trucks, with the forks of the forklift truck being insertable beneath the slip sheet.
In many of the prior art bulk box and slip sheet constructions, the slip sheet is either defined by an element completely separable from the bulk box, or is defined by an element which is a portion of the bulk box.
Examples of the use of forklift type trucks or slip sheet type trucks with bulk boxes associated with slip sheets may be seen by reference to U.S. Pat. Nos. 2,619,241 issued to Jessen; 3,142,399 issued to Oster; 3,666,128 issued to Shimizu; and, 3,850,115 issued to Mackes. Examples of bulk bin and slip sheet constructions may be seen from U.S. Pat. Nos. 4,037,775 issued to Bamburg et al; 4,138,053 issued to Gardner; and, 4,252,266, 4,358,048, 4,358,049, 4,405,077, and 4,596,355 all of which were issued to Kupersmit.